Defense lawyers for the jailed Khmer Rouge leader Nuon Chea have filed a complaint to the UN-backed tribunal, requesting the disqualification of five judges in his upcoming trial.

Among the complaints about the judges is that they failed to summon high-ranking government officials to testify in the previous phase of the trial, including Heng Samrin, president of the National Assembly, who the attorneys say would have given key testimony.

The complaint accuses Nil Nonn, head of the Trial Chamber, French judge Jean-Marc Lavergne, and three other judges of “bias” and requests they be disqualified from the impending trial phase for Nuon Chea.

A tribunal spokesman said the complaint, which was filed Sept. 29, will be examined within three months of its filing, but the second phase of the atrocity crimes trial of Nuon Chea and Khieu Samphan will continue as scheduled.